I replaced the light switch on the subzero 550 and

On sub Zero's this has been a common problem. Pressing with your finger to test isn't good enough. You have to test the switch function, by slowly closing the door to see if the DOOR turns off the lights.
There are so many lights in the food compartment producing so much heat that if the lights are on with the door closed, it will not cool.
When I run into this problem, which is common, I take a thin plastic shim
and tape it on the part of the door that hits the switch. 2" x 3" shim will
work well. If that solves the problem, I put a few drops of crazy glue on the shim and remove the tape a day later.
If the switch has 4 wires to it, the second 2 wires run the fan in the fresh food compartment. You can test that by pressing the switch and listening to see if you can hear the fan in the fresh food compartment start up.